Google's AdWords was already an auction-based advertising system by 2006, with bids and click-through rates feeding into ad placement.

Format Online paper / PDF

Location PART 2 - FOUR HIDDEN CHIMNEYS CHAPTER 9: ARE UNICORNS REALLY WHITE? From Connecting to Selling Us

"Google’s AdWords was already an auction-based advertising system by 2006, with bids and click-through rates feeding into ad placement."

Google described AdWords as an auction-based advertising program and explained that advertiser bids, click-through rates, and other relevance factors affected ad ranking.

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Source title Google Inc. Form 10-K for the Fiscal Year Ended December 31, 2005

Source authors Google Inc.

Source year 2006

Confidence high

Importance high